This invention relates to pressure-sensitive adhesives and more particularly to additives to enhance their performance.
Normally tacky, pressure sensitive adhesives (PSAs) are used in manufacturing articles such as adhesive tapes and other materials intended to be easily attached to a substrate by applying pressure alone. The adhesives are in the form of coatings of pressure-sensitive resins, typically acrylic copolymers, which are formed by casting them from organic solvent solutions and evaporating the solvent. PSAs usually have a balance of performance properties such as adhesion, cohesion, elongation, elasticity, etc. Maintaining the balance of such properties while improving one or more others is difficult and unpredictable. Improving one property may deleteriously affect one or more other desirable properties. For instance, high temperature resistance is a typical demand imposed on PSAs normally intended for use at ambient conditions. Also, for special applications, a PSA may be required to bond to a plasticized vinyl substrate and remain firmly bonded after contact over an extended period.
A continuing need exists to improve heat and plasticizer resistance of PSAs without adversely affecting other properties.